From 28149e11c844d5ebe60e24f3fdb7a02660773dc3 Mon Sep 17 00:00:00 2001
From: "Ryan C. Gordon" <icculus@icculus.org>
Date: Tue, 10 Oct 2017 11:56:54 -0400
Subject: [PATCH] Added SDL_PeekIntoDataQueue().

---
 src/SDL_dataqueue.c | 25 +++++++++++++++++++++++++
 src/SDL_dataqueue.h |  1 +
 2 files changed, 26 insertions(+)

diff --git a/src/SDL_dataqueue.c b/src/SDL_dataqueue.c
index db1adaad8e719..84370fcbccac6 100644
--- a/src/SDL_dataqueue.c
+++ b/src/SDL_dataqueue.c
@@ -225,6 +225,31 @@ SDL_WriteToDataQueue(SDL_DataQueue *queue, const void *_data, const size_t _len)
     return 0;
 }
 
+size_t
+SDL_PeekIntoDataQueue(SDL_DataQueue *queue, void *_buf, const size_t _len)
+{
+    size_t len = _len;
+    Uint8 *buf = (Uint8 *) _buf;
+    Uint8 *ptr = buf;
+    SDL_DataQueuePacket *packet;
+
+    if (!queue) {
+        return 0;
+    }
+
+    for (packet = queue->head; len && packet; packet = packet->next) {
+        const size_t avail = packet->datalen - packet->startpos;
+        const size_t cpy = SDL_min(len, avail);
+        SDL_assert(queue->queued_bytes >= avail);
+
+        SDL_memcpy(ptr, packet->data + packet->startpos, cpy);
+        ptr += cpy;
+        len -= cpy;
+    }
+
+    return (size_t) (ptr - buf);
+}
+
 size_t
 SDL_ReadFromDataQueue(SDL_DataQueue *queue, void *_buf, const size_t _len)
 {
diff --git a/src/SDL_dataqueue.h b/src/SDL_dataqueue.h
index a5e3e1c60e237..8f135c0cfc6bc 100644
--- a/src/SDL_dataqueue.h
+++ b/src/SDL_dataqueue.h
@@ -31,6 +31,7 @@ void SDL_FreeDataQueue(SDL_DataQueue *queue);
 void SDL_ClearDataQueue(SDL_DataQueue *queue, const size_t slack);
 int SDL_WriteToDataQueue(SDL_DataQueue *queue, const void *data, const size_t len);
 size_t SDL_ReadFromDataQueue(SDL_DataQueue *queue, void *buf, const size_t len);
+size_t SDL_PeekIntoDataQueue(SDL_DataQueue *queue, void *buf, const size_t len);
 size_t SDL_CountDataQueue(SDL_DataQueue *queue);
 
 /* this sets a section of the data queue aside (possibly allocating memory for it)